Swollen gums are almost always a sign of inflammation, most commonly triggered by bacterial buildup along the gumline. But the cause isn’t always poor brushing. Hormonal shifts, certain medications, infections, and chronic conditions like diabetes can all make gum tissue puff up, turn red, or bleed. Figuring out which category you fall into is the first step toward getting it to stop.
Plaque Buildup Is the Most Common Cause
The majority of gum swelling comes down to plaque, the sticky film of bacteria that forms on teeth throughout the day. When plaque sits along the gumline for too long, cells in your gum tissue detect a shift in the balance of bacteria in your mouth. Specifically, mobile bacterial species that exist at low levels in a healthy mouth begin to multiply. Your gum cells respond by switching on an inflammatory signal that brings blood flow, fluid, and immune cells to the area. That immune response is what creates the swelling, redness, and tenderness you see and feel.
This early stage of gum disease is called gingivitis. It affects a huge portion of adults and often causes no pain at all, which is why many people don’t realize they have it. The main signs are gums that look puffy or darker red than usual and bleed when you brush or floss. The good news: gingivitis is fully reversible. Consistent brushing, daily flossing, and a professional cleaning can resolve the swelling within one to two weeks for most people.
If gingivitis goes untreated, it can progress to periodontitis. At this stage, the gums start pulling away from the teeth, forming pockets that trap more bacteria and become infected. Periodontitis can cause loose teeth, receding gums, pain while chewing, and persistent bad breath. Unlike gingivitis, periodontitis damages the bone and tissue supporting your teeth, and that damage can’t be fully reversed.
Medications That Cause Gum Overgrowth
Some prescription drugs cause the gum tissue itself to grow excessively, a condition called gingival overgrowth. About 40 to 50% of patients taking certain medications develop some degree of it. The swelling typically starts between the teeth and can eventually cover portions of the tooth surface if left unchecked.
Three drug categories are the most common culprits. Seizure medications are the best known offenders: roughly half of patients taking phenytoin develop gum overgrowth. Blood pressure medications in the calcium channel blocker family also carry significant risk. Nifedipine causes it in about 38% of users, diltiazem in around 20%, and other drugs in the same class at lower rates. Immunosuppressant drugs taken after organ transplants carry an incidence ranging from 13 to 85% depending on the study.
If you started a new medication in the weeks or months before your gums began swelling, that’s worth mentioning to both your doctor and your dentist. In many cases, switching to a different drug in the same class reduces or eliminates the overgrowth, though your gums may also need professional treatment to return to normal.
Hormonal Changes During Pregnancy and Puberty
Rising levels of estrogen and progesterone make gum tissue significantly more reactive to the bacteria that are already in your mouth. Estrogen increases the permeability of blood vessels in the gums, allowing more fluid to accumulate in the tissue. Progesterone, meanwhile, suppresses the local immune cells that normally keep bacterial plaque in check. The combination means that even a normal amount of plaque can trigger a disproportionate inflammatory response.
Pregnancy gingivitis affects 60 to 70% of pregnant women and typically becomes noticeable in the second trimester. The gums may swell, bleed easily, and feel tender, even in women who had no gum problems before. Similar (though usually milder) changes can happen during puberty, menstruation, and menopause. The swelling generally improves after hormone levels stabilize, but maintaining thorough oral hygiene during these periods prevents it from progressing into something more serious.
Infections and Abscesses
If your swelling is concentrated around a single tooth rather than spread across your gumline, an abscess is a likely explanation. There are two types. A periodontal abscess forms in the gum tissue itself, usually in an existing pocket between the gum and tooth. A periapical abscess starts inside the tooth, at the tip of the root, and the infection spreads outward into the surrounding tissue. Both produce localized swelling that can be quite painful, and a periapical abscess can cause visible facial swelling on the affected side.
Abscesses don’t resolve on their own. The trapped pocket of infection needs to be drained, and the underlying cause (a deep gum pocket, a cracked tooth, or decay that has reached the nerve) needs to be treated. If you have a painful, swollen bump on your gums along with sensitivity to pressure or temperature, that warrants a prompt dental visit. Dentists diagnose abscesses through a visual exam, gentle pressure testing, and X-rays that show how far the infection has spread.
Diabetes and Blood Sugar Control
People with diabetes are three times more likely to develop periodontal disease than those without it. Persistently elevated blood sugar impairs the body’s ability to fight infection and promotes chronic inflammation in the mouth. Higher glucose levels in saliva also feed harmful oral bacteria, accelerating plaque buildup and making gum tissue break down faster.
The relationship runs in both directions. Untreated gum disease creates chronic, low-grade inflammation throughout the body, which can worsen insulin resistance and make blood sugar harder to control. Treating gum disease has been shown to reduce systemic inflammation and improve metabolic health. If you have diabetes and notice your gums are frequently swollen or bleeding, getting periodontal treatment isn’t just about your mouth. It can have a measurable effect on your overall blood sugar management.
Other Contributing Factors
Vitamin deficiencies, particularly vitamin C, can cause gums to swell and bleed easily. Smoking reduces blood flow to the gums, masks early warning signs like bleeding, and makes gum disease progress faster once it starts. Poorly fitting dentures or orthodontic appliances can irritate gum tissue and create localized swelling. Mouth breathing, often caused by nasal congestion or sleep habits, dries out gum tissue and increases inflammation along the front teeth.
What Recovery Looks Like
For straightforward gingivitis, consistent home care (twice-daily brushing with a soft-bristled brush, daily flossing, and an antiseptic rinse) can noticeably reduce swelling within a week or two. If plaque has hardened into tarite that you can’t remove at home, a professional cleaning is the next step.
For more advanced cases requiring deep cleaning (scaling and root planing, where the dentist cleans below the gumline), expect about 5 to 7 days of healing time. You may have minor soreness, swelling, and tooth sensitivity during that window, but these effects typically fade quickly. Your dentist will likely schedule a follow-up visit a few weeks later to check that the gum pockets are shrinking and the tissue is reattaching properly.
Gum swelling caused by medications or hormonal changes follows a different timeline. Medication-related overgrowth often requires a combination of professional removal of excess tissue and a conversation with your prescribing doctor about alternative drugs. Hormone-related swelling tends to improve on its own once the hormonal trigger passes, though diligent cleaning prevents lasting damage in the meantime.